Surgical instruments of this type are used for cutting through tissues that offer resistance, such as cartilage. In particular, such instruments are used for severing the cartilage of the meniscus. In a known surgical instrument of this type (Rotary Basket Punch, by Acufex Microsurgical, Inc., Boston, Mass.), the U-shaped curette, which acts as the stationary cutting part, is secured to the tube with the end of one of the legs of the U. The ends of the two legs of the U are connected with one another via a crosspiece, by means of which the end of the leg of the U remote from the tube is also connected with the tube. The movable cutting part is mounted on the end of the rotating rod that protrudes freely out of the tube. To generate the cutting movement, an actuating handle is moved toward a stationary handle part connected with the tube, whereupon the actuating handle rotates the rotating rod relative to the tube.
If strong cutting forces are exerted with this known instrument, as must necessarily be done to sever the meniscus cartilage, for instance, which is up to 4 mm thick, then the geometry of the cutting edges becomes deformed, particularly in the vicinity of the leg of the U remote from the tube, because the free end of the rotating rod supporting the cutting part and the leg of the U of the curette remote from the tube, which is supported only by the connecting crosspiece, are forced apart from one another.